218 Mr. J. E. Gray on the Howling Monkeys. 
specimens which we have in the British Museum should be ac- 
curately described, leaving the consideration of the permanence of 
the distinctions pomted out to be determined at some future time, 
or by a person more fortunately placed for such a purpose. In 
examining the species, I have been mduced to believe that the 
manner in which the hai of the forehead is directed offers 
perhaps a better character for the separation of the species than 
that of the colour, or the length, softness or stiffness of the hairs ; 
IT have therefore used it to divide the species or varieties into two 
groups, though it separates specimens of nearly the same colour 
and external appearance ; and I am aware that sometimes the hair 
of the forehead has its direction more or less changed by the 
animal-preserver ; yet, as far as I have been able to examine 
these animals, it appears to afford a very available character. 
The next character in importance appears to be the length and 
softness, or the stiffness of the hairs of the fur ; unfortunately, 
the different degrees of this character are not easily expressed in 
words. In most of the species the hair is of one colour, appear- 
mg more or less annulated from the shght curl or rather wave in 
the hair; but in others it is darker at the base, and one species 
has an obscure indication of a paler central ring. 
I shall now proceed to characterize the different specimens in 
the British Museum collection, premising, that for the purpose 
of coming to a more correct conclusion as to their distinctness, 
I have examined all the specimens which have come under my 
observation in other Enghsh and continental museums. I may 
remark that measurements are of little importance, as the adults 
of all the specimens are nearly of the same size, and as nearly as 
one can judge from stuffed specimens, the limbs, &c. are nearly 
of the same proportion. 
I. Forehead high, with the hair reflexed, forming a ridge across 
the centre of the head. 
1. The Araguata or Brown Howler, Mycetes ursinus, Pr. Max. 
Abbild. t. Stmia ursina, Humb. Obs. t. 30. S.Guariba, Humb. 
Obs. Zool. MM. fuscus, Kuhl, Beytr.; Spix, Braz. t. 30. brown 
var.; M. stramineus, Spix, Braz. t.31. yellow var.; M. barbatus, 
foem., Spix, Braz. t. 33 ? yellow var. ? 
Brown or blackish, yellow-washed ; hairs rather rigid, brown 
with yellowish tips. 
Inhab. Brazils and British Guiana. 
We have two males and two females of this species ; one of the 
latter is young and the other adult. One male is yellow, with 
the tail, hands and feet, the sides of the head, body and limbs 
